Slash is unix directory separator, so they are not allowed in filenames.
Note this also stops the classic escape via "../".

Fixes: CVE-2018-16867
Reported-by: Michael Hanselmann (hansmi.ch)
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 hw/usb/dev-mtp.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/hw/usb/dev-mtp.c b/hw/usb/dev-mtp.c
index fbe1ace035..87eeac1084 100644
--- a/hw/usb/dev-mtp.c
+++ b/hw/usb/dev-mtp.c
@@ -1718,6 +1718,12 @@ static void usb_mtp_write_metadata(MTPState *s)
 
     filename = utf16_to_str(dataset->length, dataset->filename);
 
+    if (strchr(filename, '/')) {
+        usb_mtp_queue_result(s, RES_INVALID_PARAMETER, d->trans,
+                             0, 0, 0, 0);
+        return;
+    }
+
     o = usb_mtp_object_lookup_name(p, filename, dataset->length);
     if (o != NULL) {
         next_handle = o->handle;
-- 
2.9.3

On 30/11/18 12:12, Gerd Hoffmann wrote:
> Slash is unix directory separator, so they are not allowed in filenames.
> Note this also stops the classic escape via "../".
> 
> Fixes: CVE-2018-16867
> Reported-by: Michael Hanselmann (hansmi.ch)

It's common for scripts to match '<email>', can you write this one as
Michael Hanselmann <hansmi.ch>?

(Same suggestion applies for patch 1/2).

> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  hw/usb/dev-mtp.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/hw/usb/dev-mtp.c b/hw/usb/dev-mtp.c
> index fbe1ace035..87eeac1084 100644
> --- a/hw/usb/dev-mtp.c
> +++ b/hw/usb/dev-mtp.c
> @@ -1718,6 +1718,12 @@ static void usb_mtp_write_metadata(MTPState *s)
>  
>      filename = utf16_to_str(dataset->length, dataset->filename);
>  
> +    if (strchr(filename, '/')) {
> +        usb_mtp_queue_result(s, RES_INVALID_PARAMETER, d->trans,
> +                             0, 0, 0, 0);
> +        return;
> +    }

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

> +
>      o = usb_mtp_object_lookup_name(p, filename, dataset->length);
>      if (o != NULL) {
>          next_handle = o->handle;
> 

On 11/30/18 1:08 PM, Philippe Mathieu-Daudé wrote:
> On 30/11/18 12:12, Gerd Hoffmann wrote:
>> Slash is unix directory separator, so they are not allowed in filenames.
>> Note this also stops the classic escape via "../".
>>
>> Fixes: CVE-2018-16867
>> Reported-by: Michael Hanselmann (hansmi.ch)
> 
> It's common for scripts to match '<email>', can you write this one as
> Michael Hanselmann <hansmi.ch>?

That's not an email address, though. Do we have an email for Michael, or 
just a username?

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

On 30/11/18 20:58, Eric Blake wrote:
> On 11/30/18 1:08 PM, Philippe Mathieu-Daudé wrote:
>> On 30/11/18 12:12, Gerd Hoffmann wrote:
>>> Slash is unix directory separator, so they are not allowed in filenames.
>>> Note this also stops the classic escape via "../".
>>>
>>> Fixes: CVE-2018-16867
>>> Reported-by: Michael Hanselmann (hansmi.ch)
>>
>> It's common for scripts to match '<email>', can you write this one as
>> Michael Hanselmann <hansmi.ch>?
> 
> That's not an email address, though. Do we have an email for Michael, or
> just a username?
> 

I did not notice hehe :)

Per the gpg key: Michael Hanselmann <public@hansmi.ch>
Per git commits: Michael Hanselmann <hansmi@vshn.ch>

Cc'ed him so he can decide/confirm.

On 01.12.18 12:55, Philippe Mathieu-Daudé wrote:
> On 30/11/18 20:58, Eric Blake wrote:
>> On 11/30/18 1:08 PM, Philippe Mathieu-Daudé wrote:
>>> On 30/11/18 12:12, Gerd Hoffmann wrote:
>>>> Slash is unix directory separator, so they are not allowed in filenames.
>>>> Note this also stops the classic escape via "../".
>>>>
>>>> Fixes: CVE-2018-16867
>>>> Reported-by: Michael Hanselmann (hansmi.ch)
>>>
>>> It's common for scripts to match '<email>', can you write this one as
>>> Michael Hanselmann <hansmi.ch>?
>>
>> That's not an email address, though. Do we have an email for Michael, or
>> just a username?
>>
> 
> I did not notice hehe :)
> 
> Per the gpg key: Michael Hanselmann <public@hansmi.ch>
> Per git commits: Michael Hanselmann <hansmi@vshn.ch>

It'd be <public@hansmi.ch> for this one. Thanks for asking!

Best regards,
Michael

-- 
https://hansmi.ch/

Gerd Hoffmann <kraxel@redhat.com> writes:

> Slash is unix directory separator, so they are not allowed in filenames.
> Note this also stops the classic escape via "../".
>
> Fixes: CVE-2018-16867
> Reported-by: Michael Hanselmann (hansmi.ch)
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  hw/usb/dev-mtp.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/hw/usb/dev-mtp.c b/hw/usb/dev-mtp.c
> index fbe1ace035..87eeac1084 100644
> --- a/hw/usb/dev-mtp.c
> +++ b/hw/usb/dev-mtp.c
> @@ -1718,6 +1718,12 @@ static void usb_mtp_write_metadata(MTPState *s)
>  
>      filename = utf16_to_str(dataset->length, dataset->filename);
>  
> +    if (strchr(filename, '/')) {
> +        usb_mtp_queue_result(s, RES_INVALID_PARAMETER, d->trans,
> +                             0, 0, 0, 0);
> +        return;
> +    }
> +
>      o = usb_mtp_object_lookup_name(p, filename, dataset->length);
>      if (o != NULL) {
>          next_handle = o->handle;

Should we return PARAMETER_NOT_SUPPORTED instead of INVALID_PARAMETER ?
That's a valid response code for SendObjectInfo acc to the spec.

Bandan